net: phy: at803x: fix the wol setting functions

In commit 7beecaf7 ("net: phy: at803x: improve the WOL feature"), it
seems not correct to use a wol_en bit in a 1588 Control Register which is
only available on AR8031/AR8033(share the same phy_id) to determine if WoL
is enabled.  Change it back to use AT803X_INTR_ENABLE_WOL for determining
the WoL status which is applicable on all chips supporting wol. Also update
the at803x_set_wol() function to only update the 1588 register on chips
having it.  After this change, disabling wol at probe from commit
d7cd5e06 ("net: phy: at803x: disable WOL at probe") is no longer
needed.  Change it to just disable the WoL bit in 1588 register for
AR8031/AR8033 to be aligned with AT803X_INTR_ENABLE_WOL in probe.

Fixes: 7beecaf7

 ("net: phy: at803x: improve the WOL feature")
Signed-off-by: Li Yang <leoyang.li@nxp.com>
Reviewed-by: Viorel Suman <viorel.suman@nxp.com>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>